The present invention relates to a semiconductor device and a method for fabricating the same, and more particularly it relates to a semiconductor device including an electrode or an interconnect made from a conducting film formed, with a barrier layer disposed therebetween, on an insulating or conducting film provided on a semiconductor substrate and a method for fabricating the same.
Recently, semiconductor integrated circuits having a multi-layer interconnect structure principally made from copper films have been practically used.
A conventional method for fabricating a semiconductor device having a multi-layer interconnect structure principally made from copper films will be described with reference to FIGS. 9A, 9B, 10A and 10B.
First, as shown in FIG. 9A, an insulating film 11 having an interconnect groove is formed on a semiconductor substrate 10 of silicon, and then, a first tantalum nitride film 12 serving as a barrier layer is deposited on the bottom and the walls of the interconnect groove of the insulating film 11. Next, after forming a first copper seed layer 13 on the first tantalum nitride film 12, the first copper seed layer 13 is grown through electroplating so as to form a first copper plating layer 14. Thus, a lower interconnect composed of the first copper seed layer 13 and the first copper plating layer 14 is formed.
Next, after successively depositing a silicon nitride film 15 serving as an adhesion layer and a first interlayer insulating film 16 on the lower interconnect and the insulating film 11, a via hole 17 is formed in the first interlayer insulating film 16 and the silicon nitride film 15. Then, after forming a second interlayer insulating film 18 and a silicon oxide nitrided film 19 serving as an antireflection film on the first interlayer insulating film 16, the second interlayer insulating film 18 is etched by using the silicon oxide nitrided film 19 as a mask, so as to form an interconnect groove 20.
Then, as shown in FIG. 9B, a second tantalum nitride film 21 serving as a barrier layer is deposited on the bottoms and the walls of the via hole 17 and the interconnect groove 20 by reactive sputtering, and thereafter, a second copper seed layer 22 is formed on the second tantalum nitride film 21 by sputtering.
Subsequently, as shown in FIG. 10A, the second copper seed layer 22 is grown through the electroplating so as to form a second copper plating layer 23. Thereafter, portions of the second tantalum nitride film 21, the second copper seed layer 22 and the second copper plating layer 23 present on and above the silicon oxide nitrided film 19 are removed by chemical mechanical polishing (CMP), thereby forming a plug 24 and an upper interconnect 25 composed of the second copper seed layer 22 and the second copper plating layer 23.
However, since the adhesion between the second tantalum nitride film 21 serving as the barrier layer and the upper interconnect composed of the first copper seed layer 22 and the second copper plating layer 23 is not good, peeling is caused between the second tantalum nitride film 21 and the upper interconnect through subsequently conducted annealing, such as annealing for growing a crystal grain of copper. As a result, a void 26 is disadvantageously formed between the plug 24 and the lower interconnect as shown in FIG. 10B.
When the void 26 is formed between the plug 24 and the lower interconnect, the contact resistance between the plug 24 and the lower interconnect is largely increased.
In consideration of the aforementioned conventional problem, an object of the invention is improving the adhesion between a barrier layer and a conducting film formed on the barrier layer.
In order to achieve the object, the first semiconductor device of this invention comprises: a barrier layer formed on an insulating or conducting film provided on a semiconductor substrate; and an electrode or an interconnect made from a conducting film formed on said barrier layer, wherein an interatomic distance on an upper plane of said barrier layer and an interatomic distance on a lower plane of said conducting film are nearly equal to each other.
In the first semiconductor device, it is preferable that the barrier layer has a tetragonal crystal structure and the upper plane of the barrier layer is oriented to the (001) plane, and the conducting film has a face-centered cubic crystal structure and the lower plane of the conducting film is oriented to the (111) plane.
In the second semiconductor device of this invention comprises a barrier layer formed on an insulating or conducting film provided on a semiconductor substrate; and an electrode or an interconnect made from a conducting film formed on the barrier layer, and the barrier layer includes a tantalum film having a xcex2-crystal structure.
In the second semiconductor device of this invention, since the conducting film is formed on the barrier layer made from the tantalum film having the xcex2-crystal structure, the crystal included in the conducting film is preferentially oriented to a close-packed plane. As a result, the adhesion between the barrier layer and the conducting film can be improved.
In the second semiconductor device, it is preferred that the barrier layer is made from a multi-layer film composed of a lower first barrier layer and an upper second barrier layer, and that the first barrier layer is made from a nitride film and the second barrier layer is made from a tantalum film having a xcex2-crystal structure.
In this manner, since the insulating or conducting film can be prevented from being in direct contact with the tantalum film having the xcex2-structure, a harmful compound can be prevented from being generated through a reaction between the insulating or conducting film and the tantalum film having the xcex2-structure during subsequent annealing.
In the second semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer, it is preferred that the first barrier layer is made from a tantalum nitride film and that the conducting film is a copper film.
In this manner, the copper atoms included in the copper film can be prevented from diffusing into the insulating film through the barrier layer.
In this case, the copper film is preferably oriented to the (111) plane.
Thus, the adhesion between the copper film and the tantalum film having the xcex2-structure serving as the barrier layer can be definitely improved.
Also in this case, a value of (a number of nitrogen atoms)/(a number of tantalum atoms) of the tantalum nitride film is preferably 0.4 or less.
Thus, the tantalum film having the xcex2-structure can be stably deposited on the lower tantalum nitride film.
In the second semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer and the first barrier layer is made from a nitride film, the insulating or conducting film is preferably an insulating film including a fluorine component.
In this manner, an insulating film having a low dielectric constant can be provided below the electrode or the interconnect made from the conducting film, and hence, the capacitance of the electrode or the interconnect can be lowered. Furthermore, since the first barrier layer is made from a nitride film, tantalum fluoride can be prevented from being generated through a reaction between fluorine included in the insulating film and the tantalum film having the xcex2-structure during subsequent annealing.
In the second semiconductor device, it is preferred that the insulating or conducting film is an insulating film, that the barrier layer is formed on a bottom and walls of a recess formed in the insulating film, and that the conducting film is a plug or a buried interconnect filled in the recess on the barrier layer.
In this manner, peeling between the plug or the buried interconnect and the barrier layer can be prevented so as not to form a void therebetween.
The first method of fabricating a semiconductor device of this invention comprises the steps of: forming a barrier layer on an insulating or conducting film provided on a semiconductor substrate; and forming an electrode or an interconnect made from a conducting film on said barrier layer, wherein an interatomic distance on an upper plane of said barrier layer and an interatomic distance on a lower plane of said conducting film are nearly equal to each other.
In the first method of fabricating a semiconductor device, it is preferable that the barrier layer has a tetragonal crystal structure and the upper plane of the barrier layer is oriented to the (001) plane, and the conducting film has a face-centered cubic crystal structure and the lower plane of the conducting film is oriented to the (111) plane.
The second method for fabricating a semiconductor device of this invention comprises the steps of forming a barrier layer on an insulating or conducting film provided on a semiconductor substrate; and forming an electrode or an interconnect made from a conducting film on the barrier layer, and the barrier layer includes a tantalum film having a xcex2-crystal structure.
In the second method for fabricating a semiconductor device of this invention, since the conducting film is formed on the barrier layer made from the tantalum film having the xcex2-crystal structure, the crystal included in the conducting film is preferentially oriented to a close-packed plane. As a result, the adhesion between the barrier layer and the conducting film can be improved.
In the second method for fabricating a semiconductor device, it is preferred that the barrier layer is made from a multi-layer film composed of a lower first barrier layer and an upper second barrier layer, and that the first barrier layer is made from a nitride film and the second barrier layer is made from a tantalum film having a xcex2-crystal structure.
In this manner, since the insulating or conducting film can be prevented from being in direct contact with the tantalum film having the xcex2-structure, a harmful compound can be prevented from being generated through a reaction between the insulating or conducting film and the tantalum film having the xcex2-structure during subsequent annealing.
In the second method for fabricating a semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer, it is preferred that the first barrier layer is made from a tantalum nitride film and that the conducting film is a copper film.
In this manner, the copper atoms included in the copper film can be prevented from diffusing into the insulating film through the barrier layer.
In this case, the copper film is preferably oriented to the (111) plane.
Thus, the adhesion between the copper film and the tantalum film having the xcex2-structure serving as the barrier layer can be definitely improved.
Also in this case, a value of (a number of nitrogen atoms)/(a number of tantalum atoms) of the tantalum nitride film is preferably 0.4 or less.
Thus, the tantalum film having the xcex2-structure can be stably deposited on the lower tantalum nitride film.
In the second method for fabricating a semiconductor device, in the case where the barrier layer is made from the multi-layer film composed of the lower first barrier layer and the upper second barrier layer and the first barrier layer is made from a nitride film, the insulating or conducting film is preferably an insulating film including a fluorine component.
In this manner, an insulating film having a low dielectric constant can be provided below the electrode or the interconnect made from the conducting film, and hence, the capacitance of the electrode or the interconnect can be lowered. Furthermore, since the first barrier layer is made from a nitride film, tantalum fluoride can be prevented from being generated through a reaction between fluorine included in the insulating film and the tantalum film having the xcex2-structure during subsequent annealing.
In the second method for fabricating a semiconductor device, it is preferred that the insulating or conducting film is an insulating film, that the barrier layer is formed on a bottom and walls of a recess formed in the insulating film, and that the conducting film is a plug or a buried interconnect filled in the recess on the barrier layer.
In this manner, peeling between the plug or the buried interconnect and the barrier layer can be prevented so as not to form a void therebetween.